Coinsurance
Also called: co-insurance, cost sharing percentage
Coinsurance is the percentage of a bill you pay after meeting the deductible — 20% coinsurance means the insurer covers 80%. Unlike a copay it scales with the cost, so a serious hospital stay can produce a very large share before the out-of-pocket maximum stops it. In property insurance the word means something different: a clause penalising you for insuring a building for less than a set fraction of its value.